Still image pickup device and pickup method

ABSTRACT

The present invention concerns a digital still camera ( 1 ). This camera carries out a framing process by using an infrared pick-up image and a visible light photographing by using a flash or a low speed shutter in a still image pick-up process. Upon automatic focusing, the light of an auxiliary visible light source ( 23 ) for automatic focusing is emitted to apply the visible lights and carry out an automatic focusing process. In the digital still camera, the framing process can be carried out which allows the image of a subject which is to be picked up to be displayed on a finder even under an environment of low illuminance such as photographing a dark place and a user to recognize the contents of the photographed image. Further, after that, even when the visible light photographing is carried out through the irradiation of flash or the low speed shutter, an accurate focusing can be realized.

TECHNICAL FIELD

The present invention relates to a still image pick-up device and methodfor electronically picking-up a still image by using a photoelectricconverter such as a CCD (Charge Coupled Device) image sensor.

BACKGROUND ART

An electronic still image pick-up device called the so-called digitalstill camera that employs an image sensor as a photoelectric converterhas been hitherto widely used.

In such a digital still camera, as well as a camera with a usual silversalt film, a flash function or a low speed shutter function or the likeare likewise provided in order to supplement for the shortage of thequantity of light under an environment of low illuminance such as atnight or a dark place. The flash function is a function for emitting aflash of strong light to apply light to a subject by using a dischargetube such as a xenon lamp. Further, the low speed shutter functionindicates a function for performing charge storage in the CCD for a longtime.

In the digital still camera, when an image detected by the CCD isdisplayed on, for instance, a liquid crystal panel used as a finder, theimage of the subject before it is photographed cannot be displayed onthe finder under the environment of low illuminance. That is, under theenvironment of low illuminance, even when a still image can bephotographed, a user cannot carry out a framing process to display apicked-up image on the finder so that the user may recognize theposition of the subject or a composition before the user photographs thesubject.

In order to solve the above-described problem, a digital still camerahaving an infrared photographing function that a subject is irradiatedwith infrared rays and a framing process is performed while an infraredcut filter is retracted from an optical path has been recently proposed.

FIG. 1 shows the wavelength sensitivity characteristics A of a CCD andthe wavelength passing characteristics B of an infrared cut filter. Asshown in FIG. 1, the CCD has an adequate sensitivity not only forvisible lights, but also for infrared rays having the wavelength ofabout 700 nm or more. On the contrary, the infrared cut filter does notpass the infrared rays having the wavelength of 700 nm or more. In anordinary photographing, since an exposure under infrared rays isprohibited, the infrared cut filter is inserted into the optical path oflight for photographing an image. On the other hand, in an infraredphotographing, the infrared cut filter is retracted outside the opticalpath, further, a subject is irradiated with infrared rays from infraredlight emitting means provided in a camera main body and reflected lightsthereof are photographed. Accordingly, in the digital still camerahaving such an infrared photographing function, the infraredphotographing is carried out in framing process. Upon still imagephotographing, an emission of infrared rays is stopped and a visiblelight photographing is carried out by using a flash function or a lowspeed shutter function instead thereof. Thus, even under the environmentof low illuminance, the position of the subject or a composition can berecognized before the subject is photographed and the subject can be putin a frame as desired by a user.

The digital still camera ordinarily has an automatic focusing functionthat a focalization is automatically made. The automatic focusing systemof the digital still camera includes various systems. As one of them,there is a self-focus detecting system using image characteristics thata focused image has more high frequency components than those of ahardly focused image. The self-focus detecting system is a system thatthe high frequency components for an actually picked-up image aredetected while the position of a focus lens is moved and a focal pointis set to the position of the lens where the high frequency componentsare most located.

However, a chromatic aberration is present in the lens, and a focaldistance is different between the infrared radiation and the visibleradiation. Therefore, for instance, even when the image of the samesubject is picked up from the same position, the focusing position ofthe focus lens is different between in the infrared photographing and inthe visible light photographing. Accordingly, in case the infraredphotographing is carried out upon framing process and the visible lightphotographing using the flash or the like is carried out uponphotographing a still image, when the automatic focusing process iscarried out in accordance with the self-focus detecting system based ona picked up image under the infrared radiation, a blooming and dim stillimage is photographed.

Further, even when the automatic focusing process is carried out only bynatural lights with infrared rays cut, an obtained image has a very lowcontrast under a state of low illuminance. Therefore, it is difficult,in the first place, to detect the focusing position by using theself-focus detecting system.

As mentioned above, when the infrared photographing is carried out inthe framing process and the visible light photographing by using theflash or the like is carried out in the photographing a still image, itis extremely difficult to accurately perform the automatic focusingprocess for detecting the focusing position of the still image.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a still imagepick-up device and a still image pick-up method in which a framingprocess can be realized that an image of a subject which is to be pickedup is displayed on a finder even under an environment of low illuminancesuch as photographing a dark place so as to allow a user to recognizethe contents of a photographed image, and then, even when a visiblelight photographing is carried out by using the irradiation of a flashor a low speed shutter, an accurate focusing can be realized.

A still image pick-up device according to the present inventioncomprises a photoelectric converter on which image pick-up light from asubject is incident to convert the image pick-up light into an electricsignal and pick-up an image; a finder on which the image picked up bythe photoelectric converter is displayed; an infrared removing filterprovided so as to be inserted into or retracted from an optical path ofthe image pick-up light to remove the infrared components of the imagepick-up light; an infrared light emitting part for applying infraredrays to the subject; an auxiliary light applying part for applyingvisible lights to the subject; a recording part for recording a stillimage picked up by the photoelectric converter; and a main control partfor respectively controlling the parts in accordance with the switchingoperation of processes including a framing process for displaying theimage of the subject which is to be picked up on the finder; a focusingprocess for detecting the focusing position of a focus lens based on thepick-up image picked up by the photoelectric converter and a still imagepick-up process for picking up and recording the-still image. The maincontrol part controls the infrared removing optical filter to beretracted outside the optical path and infrared rays to be emitted fromthe infrared light emitting part upon framing process; the emission ofinfrared rays from the infrared light emitting part to be stopped andthe visible lights to be emitted from the auxiliary light applying partupon focusing process; and the infrared removing optical filter to beinserted into the optical path and the focus lens to be moved to thefocusing position detected during the focusing process to pick up thestill image in the still image pick-up process.

In the still image pick-up device according to the present invention,the framing process is carried out by the infrared picked-up image and avisible light photographing is carried out by using a flash or a lowspeed shutter in still image pick-up process. In automatic focusing, theemission of the infrared rays is stopped to apply auxiliary visiblelights to the subject.

A still image pick-up method according to the present invention is astill image pick-up method for electronically picking up a still imageby using a photoelectric converter. This method comprises the steps ofswitching, in accordance with the selecting operation of a user or anautomatic selection, processes including a framing process fordisplaying the image of a subject which is to be picked up on a finder;a focusing process for detecting the focusing position of a focus lensbased on the pick-up image picked up by the photoelectric converter anda still image pick-up process for picking up and recording a stillimage; retracting an infrared removing optical filter for removing theinfrared components of image pick-up light-outside an optical path andapplying infrared rays to the subject in the framing process; stoppingthe emission of infrared rays and applying auxiliary visible lights tothe subject in the focusing process; and inserting the infrared removingoptical filter onto the optical path and moving the focus lens to thefocusing position detected during the focusing process to pick up thestill image in the still image pick-up process.

In the still image pick-up method according to the present invention,the framing process is carried out by the infrared picked-up image and avisible light photographing is carried out by using a flash or a lowspeed shutter in still image pick-up process. In automatic focusing, theemission of the infrared rays is stopped to apply auxiliary visiblelights to the subject.

Still another object and specific advantages obtained by the presentinvention will be more apparent from the description of an embodiment byreferring to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing wavelength-sensitivity characteristics of aCCD and an infrared cut filter.

FIG. 2 is a block diagram of a digital still camera to which the presentinvention is applied.

FIG. 3 is a flow chart showing an operation sequence in an ordinaryoperating mode.

FIG. 4 is a flow chart showing an operation sequence in alow-illuminance operating mode.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, an example in which the present invention is applied to a digitalstill camera for electronically picking up a still image will bedescribed.

A digital still camera 1 to which the present invention is applied hassuch a structure as shown in FIG. 2.

The digital still camera 1 to which the present invention is appliedcomprises, as shown in FIG. 2, a lens part 11, a CCD 12, a timing signalgenerating circuit (TG) 13, an analog signal processing circuit 14, ananalog/digital converting circuit (A/D) 15, a digital signal processingcircuit 16, a finder 17, a recording circuit 18, a shutter releasebutton 19, a mode changing switch 20, a flash light emitting part 21, aflash driving circuit 22, an AF auxiliary light emitting part 23, an AFauxiliary light driving circuit 24, an infrared light emitting part 25,an infrared driving circuit 26 and a main control part 27.

The CCD 12 converts the image pick-up light of the image of a subjectwhich is formed on a light receiving surface through the lens part 11into an electric signal for each pixel and outputs an image signal forone screen. The image signal outputted by the CCD 12 is supplied to theanalog signal processing circuit 14.

The timing signal generating circuit 13 generates various kinds ofdriving pulses required when the CCD 12 stores and reads the imagesignal for one screen. The variety of pulses generated from the timingsignal generating circuit 113 are supplied to the CCD 12 and used astiming signals for the image pick-up process or the output process ofthe image signal.

The analog signal processing circuit 14 carries out analog processessuch as a sampling process or an amplifying process to the image signalsupplied from the CCD 12. The image signal outputted from the analogsignal processing circuit 14 is supplied to the analog/digitalconverting circuit 15.

The analog/digital converting circuit 15 samples the analog image signalsupplied from the analog signal processing circuit 14 at a prescribedsampling rate to convert the analog image signal into a digital imagesignal. The digital image signal outputted from the analog/digitalconverting circuit 15 is supplied to the digital signal processingcircuit 16.

The digital signal processing circuit 16 generates various kinds ofsignals necessary for framing, picking up a still image, automaticfocusing, photometry, etc. from the digital image signal supplied fromthe analog/digital converting circuit 15. That is, the digital signalprocessing circuit 16 generates a display image signal from an inputimage signal, for instance, in framing process, and supplies the displayimage signal to the finder 17. The digital signal processing circuit 16generates a still image signal of one frame from the input image signal,upon picking up a still image, compresses the still image signal, andthen, supplies the compressed still image signal to the recordingcircuit 18. Further, the digital signal processing circuit 16 detectsthe high frequency components of a prescribed area in a screen from theinput image signal upon automatic focusing, generates parameters showingthe high frequency components and supplies the parameters to the maincontrol part 27. Further, the digital signal processing circuit 16detects light quantity components of the prescribed area in the screenfrom the input image signal upon photometry process, generatesparameters showing the light quantity levels thereof and supplies theparameters to the main control part 27.

The finder 17 is an electronic type display device composed of, forinstance, a liquid crystal panel. To the finder 17, the display imagesignal is inputted from the digital signal processing circuit 16, inframing process, and the image signal is displayed. That is, on thefinder 17, the image of the subject which is formed on the lightreceiving surface of the CCD 12 is displayed during a time except at thetime of picking up a still image.

The recording circuit 18 records a still image signal outputted from thedigital signal processing circuit 16 on recording media such as memorycard upon picking up a still image.

The shutter release button 19 is a momentary pressing switch operated bya user. The shutter release button 19 has a function for discriminatingand switching three states including a state (off) that the switch isnot pressed, a state (completely pressed) that the switch is completelypressed and a state (half pressed) that the switch is half pressed. Thethree pressed states (off, half-pressed, completely pressed) of theshutter release button 19 are discriminated by the main control part 27.The operation of the digital still camera 1 under each pressed statewill be described below in detail.

The mode changing switch 20 is a change switch operated by the user. Themode changing switch 20 is a switch for switching the photographing modeof the digital still camera 1 to an ordinary photographing mode and alow illuminance photographing mode. The switching state of the modechange switch 20 is discriminated by the main control part 27. Theoperation of the digital still camera 1 under each mode will bedescribed below in detail.

The flash light emitting part 21 is discharging means such as xenon lampcalled a so-called strobe or speed light which can momentarily emit astrong light to apply the light to a subject. In other words, the flashlight emitting part 21 can apply a strong flash to the subject. Theflash light emitting part 21 is attached to, for instance, the frontsurface or the upper part of a casing so as to apply light to a subjectwhose image is to be picked up. That is, the flash light emitting part21 is provided to apply light in the direction of an optical axis of alens forward from the lens. The flash light emitting part 21 is drivenby the flash driving circuit 22 and its light emitting timing iscontrolled by the main control part 27.

The AF auxiliary light emitting part 23 is visible light emitting meansfor emitting visible lights such as a light emitting diode, a laserlight emitting part, a lamp, etc. The AF auxiliary light emitting part23 is different from the flash light emitting part 21 and does notmomentarily emit light, but continuously emits a substantiallyprescribed quantity of visible lights. This AF auxiliary light emittingpart 23 is also attached to, for instance, the front surface or theupper part of a casing so as to emit light to a subject whose image isto be picked up. That is, the AF auxiliary light emitting part 23 isprovided to apply light in the direction of an optical axis of the lensforward from the lens. The AF auxiliary light emitting part 23 is drivenby the AF auxiliary light driving circuit 24 and its light emittingtiming is controlled by the main control part 27.

The infrared light emitting part 25 is light emitting means for infraredrays. The infrared light emitting part 25 is likewise different from theflash light emitting part 21 and does not momentarily emit light, butcontinuously emits a substantially prescribed quantity of infrared rays.The infrared light emitting part 25 is also attached to, for instance,the front surface or the upper part of a casing so as to emit light to asubject whose image is to be picked up. That is, the infrared lightemitting part 25 is provided to apply light in the direction of anoptical axis of the lens forward from the lens. The infrared lightemitting part 25 is driven by the infrared driving circuit 26 and itslight emitting timing is controlled by the main control part 27.

The main control part 27 controls the respective parts of the digitalstill camera 1.

The lens part 11 includes a zoom lens 31, a focusing lens 32, aninfrared cut filter 33, diaphragm blades 34 and shutter blades 35. Thesemembers form an optical system for forming an image of the image pick-uplight from the subject on the light receive surface of the CCD 12.Further, the lens part 11 includes a zoom lens driving part 41 fordriving the zoom lens 31, a focusing lens driving part 42 for drivingthe focusing lens 32, a filter driving circuit 43 for driving theinfrared cut filter 33, a diaphragm driving part 44 for driving thediaphragm blades 34 and a shutter driving part 45 for driving theshutter blades 35.

The zoom lens 31 is provided at a position where its optical axiscorresponds to a vertical line extended from a substantially centralpart of the light receive surface of the CCD 12. The zoom lens 31 isprovided so as to be linearly movable forward and backward on theoptical axis. The image pick-up magnification of an image formed on thelight receiving surface of the CCD 12 is changed in accordance with themoving position of the zoom lens 31. The moving position of the zoomlens 31 is controlled by the main control part 27 through the zoom lensdriving part 41.

The focusing lens 32 is provided at a position where its optical axiscorresponds to a vertical line extended from a substantially centralpart of the light receive surface of the CCD 12. The focusing lens 32 isprovided so as to be linearly movable forward and backward on theoptical axis. The focusing position of an image formed on the lightreceiving surface of the CCD 12 is changed in accordance with the movingposition of the focusing lens 32. The moving position of the focusinglens 32 is controlled by the main control part 27 through the focusinglens driving part 42.

The infrared cut filter 33 is provided so as to be selectively switchedto be retracted from or inserted into the optical path of image pick-uplight whose image is formed on the light receiving surface of the CCD12. Here, the insertion of the infrared cut filter 33 into the opticalpath means that the infrared cut filter 33 is arranged at a positionwhere the image pick-up light whose image is formed on the imagereceiving surface of the CCD 12 passes. Further, the retraction of theinfrared cut filter from the optical path of the image pick-up lightmeans that the infrared cut filter 33 is arranged at a position wherethe image pick-up light whose image is formed on the light receivingsurface of the CCD 12 does not pass. The infrared cut filter 33 is anoptical filter for removing infrared rays from incident light and hasoptical characteristics of interrupting light of wavelength longer thanabout 700 nm as shown, for instance, in FIG. 1. Accordingly, when theinfrared cut filter 33 is inserted into the optical path, the image ofthe image pick-up light from which the light of wavelength not shorterthan infrared rays is removed is formed on the light receiving surfaceof the CCD 12. When the infrared cut filter 33 is retracted from theoptical path of the image pick-up light, the image of the image pick-uplight from which the infrared rays are not removed is directly formed onthe light receiving surface of the CCD 12. The infrared cut filter 33 iscontrolled to be switched to be inserted or retracted by the maincontrol part 27 through the filter driving part 43.

The diaphragm blades 34 adjust the quantity of the image pick-up lightwhose image is formed on the light receive surface of the CCD 12. Thediaphragm blades 34 form an aperture on the optical axis of the opticalsystem of the lens part 11 as a center and control the quantity of lightby changing the aperture size. That is, the diaphragm blades 34 controla diaphragm value (F-number) of the camera. The diaphragm value of thediaphragm blades 34 is controlled by the main control part 27 throughthe diaphragm driving part 44.

The shutter blades 35 are provided on the optical path of the imagepick-up light whose image is formed on the light receiving surface ofthe CCD 12 to interrupt the image pick-up light by opening or closingthe blades. The shutter blades 35 open the image pick-up light for aprescribed time upon picking up a still image. At that time, the chargestorage time (electronic shutter) of the CCD 12 is controlled and theapplying time of light whose image is formed on the light receivesurface is controlled. The shutter speed of the camera at the time ofpicking up the still image is controlled by the electronic shutter. Theopening and closing timing of the shutter blades 35 is controlled by themain control part 27 through the shutter driving part 45.

Now, the operation of the digital still camera 1 according to thepresent invention will be described below.

The digital still camera 1 according to the present invention carriesout a framing process, an automatic focusing process and a still imagepick-up process in accordance with the states (off, half-pressed,completely pressed) of the shutter release button 19.

The framing process is a process that an image picked up by the CCD 12is displayed on the finder 17 so that a user can recognize the positionof a subject in a screen or the composition of the screen before theuser photographs the subject. In the framing process, the CCD 12performs an image pick-up process for one screen at intervals ofprescribed time (for instance, at intervals of − 1/30 seconds) and thepicked-up and obtained image signal is outputted. Consequently, theimage displayed on the finder 17 is also updated at intervals ofprescribed time (for instance, at intervals of 1/30 seconds). Thus, theuser can recognize the pick-up image displayed on the finer 17 as amoving image. This framing process is carried out when the digital stillcamera 1 itself is brought into a state in which a photographingoperation can be done and the shutter release button 19 is in a state ofoff, in other words, the user does not press the shutter release button19.

The automatic focusing process is a process for automatically settingthe focus of the image of the subject as a subject of a still image tobe picked up. That is, the automatic focusing process is a process forautomatically adjusting a focal point. While the framing process iscarried out, when the shutter release button 19 is half pressed, thedigital still camera 1 starts the automatic focusing process of what iscalled a self-focus detecting system that the focusing position isdetected based on the picked-up image. When the digital still camera 1starts the automatic focusing process, the main control part 27 controlsthe focusing lens 32 to be sequentially moved and pick up the image ofthe subject. Then, the digital signal processing circuit 16 measureshigh frequency components in a part of a range (focus measuring area) inthe screen from each picked up image and detects parameters showing thelevels of the high frequency components included in the area. Then, themain control part 27 detects the moving position of the focusing lens 32in which the parameters become the highest and sets the moving positionas the focusing position.

In the digital still camera 1, for instance, the opening degree of thediaphragm blades 34 or the electronic shutter or the like is set as wellas the automatic focusing process, that is, a quantity of exposure lightnecessary for setting the F-number or shutter speed is likewise measured(photometry). Further, other setting such as the setting of whitebalance necessary for photographing a still image is also carried out.

To complete the automatic focusing process, a prescribed time is needed.However, even when this process is completed, in case a user yet remainsto half press the shutter release button 19, the automatic focusingprocess will be automatically shifted to the framing process.

The still image pick-up process is a process that the image of a subjectis picked up for one screen and the image of the subject of one screenis recorded on a medium. In the digital still camera 1, when the shutterrelease button 19 is completely pressed after the automatic focusingprocess is finished, the moving position of the focusing lens 32, theopening degree of the diaphragm blades 34 and shutter time, etc. are setto values detected during the automatic focusing process to pickup astill image of one screen by the CCD 12. The picked up still image iscompressed by the digital signal processing circuit 16 or the like, andthen, stored in the media. When the still image pick-up process iscompleted, the process is shifted to the framing process again.

Further, in the digital still camera 1, the photographing mode isswitched to the ordinary photographing mode and to the low illuminancephotographing mode. In the digital still camera 1, the light emission ofthe flash light emitting part 21, the AF auxiliary light emitting part23 and the infrared light emitting part 25 is controlled and theinsertion/retraction of the infrared cut filter 33 are controlled inaccordance with the switched state of the mode.

The ordinary photographing mode is a photographing mode under anenvironment that the subject has an adequate illuminance and a stillimage can be photographed without supplementing for the shortage of thequantity of light by, for instance, the flash. On the other hand, thelow illuminance photographing mode is a photographing mode under anenvironment that an ordinary still image photographing cannot be carriedout under the environment of low illuminance such as at night or a darkplace. The main control part 27 decides to switch the ordinaryphotographing mode and the low illuminance photographing mode inaccordance with the switching state of the mode changing switch 20 orthe value of a quantity of light in an outer periphery.

Under the ordinary photographing mode, the emission of light of theflash light emitting part 21, the AF auxiliary light emitting part 23and the infrared light emitting part 25 is stopped and the infrared cutfilter 33 is inserted into the optical path of photographing light.

On the other hand, under the low illuminance photographing mode, acontrol is performed as described below during the respective processesincluding the framing process, the automatic focusing process and thestill image pick-up process.

In the framing process, the emission of light of the flash lightemitting part 21 and the AF auxiliary light emitting part 23 is stoppedand the light of the infrared light emitting part 25 is emitted.Further, the infrared cut filter 33 is retracted from the optical pathof image pick-up light. Accordingly, in framing process, infrared raysare applied to the subject and the image of reflected light is picked upby the CCD 12. Therefore, even under the state of insufficientilluminance such as at night, a picked up image necessary forrecognizing the position of the subject or a composition can bedisplayed on the finder 17.

In the automatic focusing process, the emission of light of the flashlight emitting part 21 and the infrared light emitting part 25 isstopped and the light of the AF auxiliary light emitting part 23 isemitted. Further, the infrared cut filter 33 is inserted into theoptical path of the image pick-up light. Accordingly, visible lights areapplied to the subject and an image of reflected lights therefrom ispicked up by the CCD 12. Therefore, even under the state of insufficientilluminance such as at night, the focusing position when the subject isphotographed under the visible lights can be precisely detected.

At the time of the still image pick-up process, the emission of light ofthe AF auxiliary light emitting part 23 and the infrared light emittingpart 25 is stopped and the light of the flash light emitting part 21 isemitted. Further, the infrared cut filter 33 is inserted onto theoptical path of the image pick-up light. Accordingly, an adequatequantity of light necessary for photographing a still-image is appliedto the subject and the shutter blades 35 are controlled at its lightapplying timing so that the CCD 12 can receive the visible lights.Therefore, even under the state of insufficient illuminance, forinstance, at night, the image of the subject can be electronicallypicked up.

Although the infrared cut filter 33 is inserted onto the optical path ofthe image pick-up light at the time of the automatic focusing process,the infrared cut filter 33 may be kept retracted from the optical path.In this case, the CCD 12 may possibly receive infrared components sothat the precise focusing position only by the visible lights may not beprobably detected. However, when the moving position of the focusinglens 32 is set by correcting a prescribed amount from the focusingposition detected in automatic focusing, a focused still image can bepicked up.

Further, although the light of the flash light emitting part 21 isemitted to supplement for the shortage of the quantity of light in thestill image pick-up process, the light of the flash light emitting part21 may not be emitted. Instead thereof, shutter speed may be adequatelylowered so as to supplement for the shortage of the quantity of light.

Now, an operation sequence of the digital still camera 1 will bedescribed below.

Firstly, for initialization, it is assumed that the emission of light ofthe flash light emitting part 21, the AF auxiliary light emitting part23 and the infrared light emitting part 25 is stopped and the infraredcut filter 33 is inserted onto the optical path of the image pick-uplight. Then, the main control part 27 of the digital still camera 1decides whether a photographing mode is set to an ordinary operatingmode or to a low illuminance operating mode. The main control part 27carries out a process from step S11 shown in FIG. 3 when thephotographing mode is set to the ordinary operating mode. The maincontrol part 27 carries out a process from step S31 shown in FIG. 4 whenthe photographing mode is set to the low illuminance operating mode.

Initially, the process in the ordinary operating mode will be describedby referring to a flow chart shown in FIG. 3.

When the main control part 27 of the digital still camera 1 decides thatthe photographing mode is the ordinary operating mode, the main controlpart 27 starts a framing process (step S11).

Then, when the shutter release button 19 is half pressed by a user (stepS12), the main control part 27 measures a quantity of exposure light(photometry) or the like (step S13). A photometry process is carried outto set a diaphragm value and shutter speed.

After that, the main control part 27 carries out an automatic focusingprocess (step S14). The automatic focusing process is carried out to setthe focusing position of the focusing lens 32.

Subsequently, the main control part 27 moves the focusing lens 32 to theset lens position (step S15).

Then, when the shutter release button 19 is completely pressed by theuser (step S16), the main control part 27 starts a still image pick-upprocess (step S17). When the main control part 27 starts the still imagepick-up process, the main control part 27 firstly adjusts the openingdegree of the diaphragm blades 34 to the diaphragm value set in the stepS13 (step S18).

Then, the main control part 27 opens the shutter blades 35 to start alight receive of the CCD 12 (step S19).

When a charge storage time set in the step S13 arrives after the maincontrol part 27 starts the light receive, the main control part 27 stopsthe light receive of the CCD 12 to close the shutter blades 35 (stepS20).

After that, the main control part 27 starts reading of an image signalfrom the CCD 12 (step S21).

Subsequently, the main control part 27 carries out various kinds ofprocesses to the image signal read from the CCD 12 to form a still image(step S22).

After that, the main control part 27 records the formed still image on amedium (step S23).

The still image pick-up process is completed in the step S23 and theprocess from the framing process (step S11) is repeated again.

Now, a process in the low illuminance operating mode will be describedby referring to a flow chart shown in FIG. 4.

When the main control part 27 of the digital still camera 1 decides thatthe photographing mode is the low illuminance operating mode, the maincontrol part 27 emits light of the infrared light emitting part 25 andretracts the infrared cut filter 33 from the optical path of the imagepick-up light (step S31).

Then, the main control part 27 starts a framing process (step S32).

Then, when the shutter release button 19 is half-pressed by a user (stepS33), the main control part 27 stops the emission of light of theinfrared light emitting part 25 and inserts the infrared cut filter 33onto the optical path of the image pick-up light (step S34).

Subsequently, the main control part 27 measures a quantity of exposurelight (photometry) or the like (step S35). The photometry process iscarried out to set the opening degree of a diaphragm and shutter speed.

Then, the main control part 27 emits light of the AF auxiliary lightemitting part 23 (step 36).

After that, the main control part 27 carries out an automatic focusingprocess (step S37). The automatic focusing process is carried out to setthe position of the focusing lens 32. Subsequently, the main controlpart 27 moves the focusing lens 32 to the set lens position (step S38).

After that, the main control part 27 stops the emission of light of theAF auxiliary light emitting part 23 (step S39).

Then, when the shutter release button 19 is completely pressed by a user(step S40), the main control part 27 starts a still image pick-upprocess (step S41).

When the main control part 27 starts the still image pick-up process,the main control part 27 firstly adjusts the opening degree of thediaphragm blades 34 to an diaphragm value set in the step S35 (stepS42).

After that, the main control part 27 opens the shutter blades 35 tostart the light receive of the CCD 12 (step S43).

Subsequently, the main control part 27 emits light of the flash lightemitting part 21 simultaneously with a timing at which the main controlpart 27 opens the shutter blades 35 to start the light receive of theCCD 12 (step S44).

When a charge storage time set in the step S35 arrives after the maincontrol part 27 starts the light receive, the main control part 27 stopsthe light receive of the CCD 12 to close the shutter blades 35 (stepS45).

After that, the main control part 27 starts reading of an image signalfrom the CCD 12 (step S46).

Subsequently, the main control part 27 carries out various kinds ofsignal processes to the image signal read from the CCD 12 to form astill-image (step S47).

Then, the main control part 27 records the formed still image on amedium (step S48).

The still image pick-up process is completed in the step S48 to repeatagain the process from the framing process (step S31).

As mentioned above, in the digital still camera 1 according to thepresent invention, the infrared rays are applied to the subject to carryout the framing process.

In the still image pick-up process, the visible light photographing iscarried out by using a flash. Then, in the automatic focusing process,the emission of infrared rays is stopped and auxiliary visible lightsare applied to the subject.

Consequently, the digital still camera 1 according to the presentinvention can realize the framing process that the image of the subjectwhich is to be picked up is displayed on the finder even under theenvironment of low illuminance such as at night or a dark place to allowa user to recognize the contents of the photographed image. Further,even when the flash is applied to the subject after that, a precisefocusing process without blooming can be realized.

Industrial Applicability

In the still image pick-up device and the image pick-up method accordingto the present invention, the framing process is carried out under aninfrared photographing. In the still image pick-up process, the flash orthe low speed shutter or the like is used to perform the visible lightphotographing. In the automatic focusing process, the emission ofinfrared rays is stopped and the auxiliary visible lights are applied tothe subject.

Thus, in the still image pick-up device and the still image pick-upmethod according to the present invention, the framing process can berealized that the image of the subject which is to be picked up isdisplayed on the finder even under the environment of low illuminancesuch as at night or a dark place to allow a user to recognize thecontents of the photographed image. Further, even when the flash isapplied to the subject after that, a precise focusing process withoutblooming can be realized.

1. A still image pick-up device comprising: a photoelectric converter onwhich image pick-up light from a subject is incident to convert theimage pick-up light into an electric signal and pick-up an image; afinder on which the image picked up by the photoelectric converter isdisplayed; an infrared removing filter provided so as to be insertedinto or retracted from an optical path of the image pick-up light toremove infrared components of the image pick-up light; an infrared lightemitting part for applying infrared rays to the subject; an auxiliarylight applying part for applying visible lights to the subject; arecording part for recording a still image picked up by thephotoelectric converter; and a main control part for controlling theparts in accordance with the switching operation of processes includinga framing process for displaying the image of the subject which is to bepicked up on the finder, a focusing process for detecting the focusingposition of a focus lens based on the pick-up image picked up by thephotoelectric converter and a still image pick-up process for picking upand recording a still image, wherein the main control part controls theinfrared removing optical filter to be retracted outside the opticalpath and infrared rays to be emitted from the infrared light emittingpart in the framing process, the emission of infrared rays from theinfrared light emitting part to be stopped and the visible lights to beemitted from the auxiliary light applying part in the focusing process,and the infrared removing optical filter to be inserted into the opticalpath and the focus lens to be moved to the focusing position detectedduring the focusing process to pick up a still image in the still imagepick-up process.
 2. The still image pick-up device according to claim 1,further comprising a flash applying part for applying a flash of visiblelights to the subject; wherein the main control part inserts theinfrared removing optical filter into the optical path, moves the focuslens to the focusing position detected in the focusing process andapplies the flash of visible lights from the flash applying part to thesubject to pickup a still image in the still image pick-up process. 3.The still image pick-up device according to claim 1, wherein the maincontrol part inserts the infrared removing optical filter into theoptical path to detect the focusing position of the focus lens in thefocusing process.
 4. The still image pick-up device according to claim1, wherein the main control part retracts the infrared removing opticalfilter outside the optical path to detect the focusing position of thefocus lens in the focusing process, and moves the focus lens, in thestill image pick-up process, to a position where a prescribed correctionis applied to the focusing position detected at the time of the focusingprocess.
 5. The still image pick-up device according to claim 1, furthercomprising a pressing button for switching the framing process, thefocusing process and the still image pick-up process, wherein the maincontrol part carries out the framing process when the pressing button isnot pressed, performs the focusing process when the pressing button ishalf pressed, and performs the still image pick-up process when thepressing button is completely pressed, and further, carries out theframing process after the detection of the focusing position of thefocus lens is completed while the pressing button is half pressed.
 6. Astill image pick-up method for electronically picking up a still imageby using a photoelectric converter, the method comprising the steps of:switching, in accordance with the selecting operation of a user or anautomatic selection, processes including a framing process fordisplaying the image of a subject which is to be picked up on a finder,a focusing process for detecting the focusing position of a focus lensbased on the pick-up image picked up by the photoelectric converter anda still image pick-up process for picking up and recording a stillimage; retracting an infrared removing optical filter for removinginfrared components of image pick-up light outside an optical path andapplying infrared rays to the subject in the framing process; stoppingthe emission of infrared rays and applying auxiliary visible lights tothe subject in the focusing process; and inserting the infrared removingoptical filter onto the optical path and moving the focus lens to thefocusing position detected during the focusing process to pick up astill image in the still image pick-up process.
 7. The still imagepick-up method according to claim 6, wherein the infrared removingoptical filter is inserted into the optical path and the focus lens ismoved to the focusing position detected in the focusing process to applya flash of visible lights to the subject and pick-up a still image inthe still image pick-up process.
 8. The still image pick-up methodaccording to claim 6, wherein the infrared removing optical filter isinserted into the optical path to detect the focusing position of thefocus lens in the focusing process.
 9. The still image pick-up methodaccording to claim 6, wherein the infrared removing optical filter isretracted outside the optical path to detect the focusing position ofthe focus lens in the focusing process, and the focus lens is moved to aposition where a prescribed correction is applied to the focusingposition detected during the focusing process in the still image pick-upprocess.
 10. The still image pick-up method according to claim 6,wherein when a pressing button for switching the framing process, thefocusing process and the still image pick-up process is not pressed, theframing process is carried out, when the pressing button is halfpressed, the focusing process is carried out, and when the pressingbutton is completely pressed, the still image pick-up process is carriedout, and further, after the detection of the focusing position of thefocus lens is completed while the pressing button is half pressed, theframing process is carried out.